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Discussion Starter · #1 ·
Hey all,

Im relatively new to Street Tuner, but I've been tuning GM cars with HPTuner for awhile now. Within HPtuner there are several tools available to create and work with curves that are in 2 dimensional maps and 3-dimensional surfaces. Theres smoothing, interpolation, map-wide subtraction, addition, and multiplication. Within street tuner, I have found a limited set of these tools... particularly limited by my ability to select the whole map (as far as I can tell).

What are your techniques for working smoothness (but accuracy) into the intake transfer map (MAF voltage v. Mass of air)?

Are there other tables that you have used these techniques on as well?

thanks,
Chris
 

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I have a simple excel spreadsheet that lets me add a varying percentage to the maf calibration. So for instance my current BigMAF calibration is roughly +14% at the lowest maf voltage and +32% at 5v when compared to the stock calibration.
 

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RainMaker said:
What are your techniques for working smoothness (but accuracy) into the intake transfer map (MAF voltage v. Mass of air)? Are there other tables that you have used these techniques on as well? thanks, Chris
I would be happy to send you the latest tuning guide and worksheet I have been working on. Just e-mail me [email protected] and ask for it in the Subject:

Until you get the full guide...
– Fine tune your Intake Calibration table. This table is used to tell your ECU the mass of air that is entering your engine so that you can properly calculate the mass of the fuel it needs to inject into the motor to get the air/fuel value dictated in the Primary Fuel table or by the closed loop control, 1 Lambda. Under closed loop conditions the ECU is always going to try and hit 1 Lambda or 14.7:1 A/F, which is an air mass of 14.7 to every 1 fuel mass.

Start the vehicle, let it idle, and come to temperature...it may not perfectly idle, but just deal with it until it comes to temperature, 180-190 F. Use the dashboard to pull up your A/F Trim Immed., A/F Trim Learned, MAF Voltage, and Coolant Temp. After the vehicle has come to temperature, re-set the ECU (you will be prompted to turn the vehicle off then back on). Start the motor again, and then watch your MAF voltage and A/F trims. You want the combination of your A/F trims to be as close to 0 as possible. EX = If your A/F Trim Immed. is +5% and A/F Trim Learned is 0, then simply look up the MAF Voltage, which should be close to 1.2-1.28 volts at idle, on the Intake Calibration table and adjust the grams/sec value for that voltage up (+) until your combined fuel trims are 0 or close to zero. These adjustments can be made very easily by looking at the combined % correction of the A/F Trim Immed. & A/F Trim Learned. If that total is +6% then you can highlight the Intake Calibration cell for that particular MAF voltage and hit the “M” key, you will then be prompted to enter a floating point value. The correct value for this particular situation would be 1.06; this adjustment will now tell your ECU for that particular MAF voltage you now have a 6% greater MASS of air entering the motor so 6% more mass of fuel should be injected. After this adjustment is made you’re A/F Trims should be close to zero. (If that total is -6% then you can highlight the Intake Calibration cell for that particular MAF voltage and hit the “M” key, you will then be prompted to enter a floating point value. The correct value for this particular situation would be 0.94; this adjustment will now tell your ECU for that particular MAF voltage you now have 6% less MASS of air entering the motor so 6% less mass of fuel should be injected, bringing your fuel trims close to zero.) I would shoot for a A/F Trim Learned value of +/- 5% max. You may have to re-set your ECU throughout this process to remove any learned trims. To re-set your ECU while live tuning, close down any tracing or dashboard, then you can go to the “ECU” drop down menu and select the Reset ECU option. You will be prompted to turn your vehicle fully of and back on again. When you do this, you should notice that your DAM (Dynamic Advance Multiplier) will be set back to the default value. Make sense?

Do this along the Intake Calibration table up to 2.6 volts or so ON A LOAD-BASED CHASSIS DYNO at part-throttle. Be sure to run the vehicle with the A/C on as well to make sure your calibrations are consistent. If you have a properly designed intake system the Intake Calibrations should look very similar to your stock Intake Calibration graph under the table data. Be sure to keep your throttle movement as steady as possible during this process. Rapid movements of the throttle will employ adjustments from the Tip-in Enrichment table and may skew your fuel trims.

Your trim values will always adjust back and forth (+/-); let them, that is what they are supposed to do. Do not beat yourself up trying to get them at exactly 0...it is impossible (temperature, weather, gasoline, etc. changes will not keep anything constant while you are tuning).

If you are seeing plateaus, spikes, dips, or flat spots in the graph for the Intake Calibration table then you know something is wrong...replace the intake system with a properly designed one.

NOTE: Changing the Intake Calibration table will change your calculated load output. If all other variables remain constant, the less airflow you calibrate in the ECU for a given MAF voltage; the less engine load will be calculated.

Take care,
Christian.
 

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Discussion Starter · #5 ·
WolfPlayer said:
Chris (RainMaker),

I do it the way I have done it for years: A bunch of data + a little bit of black magic (interpolation).

http://www.iwsti.com/forums/showpost.php?p=714554&postcount=8

For interpolation I like to just click and drag the points on the graph :)

t

Thanks Tim... that link describes a great method, especially for those of us who dont have a load based dyno at our disposal. I've tried similar before, adn the results were good, but as you mentioned, they are much clearer is everythign is "steady state" ie not quick throttle changes.

Is there any cute black magic available for pulling the steady state stuff out? ;)
 
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